As a head main body of a liquid discharge head used for inkjet type printing, there is a known head main body formed by laminating a flow passage member having a manifold (common flow passage) and a plurality of discharge holes which is respectively connected via a plurality of liquid pressurization chambers from the manifold, and piezoelectric actuator substrates having a plurality of displacement elements which is provided to respectively cover the liquid pressurization chambers (for example, refer to Patent Literature 1). In this head main body, by displacing the displacement elements of the piezoelectric actuator substrates, ink can be discharged from discharge holes. Four piezoelectric actuator substrates are provided, and a flexible substrate is connected to each of the piezoelectric actuator substrates. A driver IC that processes a drive signal is respectively mounted on the flexible substrate. The driver IC is in contact with an inner surface of an oblong casing of the liquid discharge head, and heat of the driver IC is removed through the casing.